I am the functional manager of a team with ten people. One of them, who is very highly skilled, has turned very hostile in the last few months towards colleagues and myself. We had a 1:1 three months ago which was very good, however just a week later her behavior didn't change. She's verbally abusive, sarcastic in her comments, aggressive in tone, creates conflicts where there's none and undermines my authority in front of others. A total nightmare. She also has expressed that she wants to quit the team.
I collected all the evidence from the past weeks (luckily she writes everything on a chat) and shared to my manager. He wanted to give her the benefit of the doubt and had meetings with her - but now she behaves the same (hostile) with him! Due to this, he scheduled a meeting with her to explain the situation and the consequences of her behavior, but she rejected the meeting and told him there's nothing she has to discuss with him (!!!)
I can only think that this behavior is the product of a serious mental disorder or something that's going on in her life that we are unaware of. My manager of course already involved HR who will start a disciplinary procedure which can led to dismissal. She is not aware of this because she refused to even talk to my manager.
Since she will be contacted by HR in the next days on this, I wonder how people who went through a similar situation dealt with that. My manager told me the situation will get very ugly for us and she will likely want to play victim and prolong the whole thing.
Clarifications:
Clarifying a few points as some people are making too many assumptions:
I brought a complaint on this employee's behavior to my manager -- and honestly he has been too nice because in retrospective he should have involved HR at least a month ago. My manager and this person have had regular weekly meetings. I don't think these meetings helped because she continued behaving the same towards me (and colleagues)
Recently she started behaving the same with my manager. Declining meetings, telling him "she has no pending topics to discuss with him" (sic), in other words, ignoring him. My manager then setup a meeting because he wanted to warn her verbally of the consequences of such behavior (i.e. HR involvement). For him, HR was the last option. But she declined the meetings (2) he put with her to inform on this, so now HR will get in the picture.
When my manager said that 'things could get ugly' for us he meant just that. We don't know how this person will react. And this person has clearly said she wants out of the team anyway, but once HR is involved she won't be able to rotate in the company (which is what she wants). She will take this very bad and may cause a big mess in our team -- not to mention she will probably want to try to turn things against us (luckily -- I have written evidence of how she behaves)
Whatever you think of the situation, or what I did or did not, I have never seen in 20+ years experience someone refusing a meeting with a manager. In other companies this person would have been fired long time ago.
I am not sure what problem this person has. But whatever problem she has, her behavior is simply unacceptable. She said she wants to leave the team (told us about this 3 months ago). The reason is that she wants to do different stuff than we currently do. Fair enough. We had a similar person in the past. He was happy with us doing XYZ but wanted to do also ABC which we couldn't offer. Now he is working in another team (same company) and happy. No issues. She could have gone the same path as him, but for whatever reason (now she will need to explain this to HR) she started behaving mad and now the situation is far from being salvable. And by the way, early when she started behaving like this, I had a 1:1, a very good one, and she seemed to understand and agree that she needs to improve. But one week later she continued with the same behavior and that point I took it with my manager.